Program crashes only when compiled via LLVM

llvm-test.hs:

import System.IO
import Foreign.Storable
import Foreign.Marshal.Alloc
import Data.Word

main = do
    hSetBuffering stdout NoBuffering

    test 1000
    test 5000
  where
    test n = do
        allocaBytes (n * 4) $ \p -> do
            sequence_ [
              pokeByteOff p (i * 4) (0x12345678 :: Word32)
              | i <- [ 0 .. n - 1 ]
              ]
        putStrLn $ show n ++ " fine"

---

Cygwin shell:

user@pc ~
$ ghc llvm-test.hs && ./llvm-test.exe
[1 of 1] Compiling Main             ( llvm-test.hs, llvm-test.o )
Linking llvm-test.exe ...
1000 fine
5000 fine

user@pc ~
$ touch llvm-test.hs

user@pc ~
$ ghc llvm-test.hs -fllvm && ./llvm-test.exe
[1 of 1] Compiling Main             ( llvm-test.hs, llvm-test.o )
Linking llvm-test.exe ...
1000 fine
Segmentation fault

---

<erikd> `Guest00000: try adding -O2 to the compiler command line.
<`Guest00000> erikd: it now segfaults even before printing "1000 fine"
<`Guest00000> wait, one time it printed one character "1" before crashing

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	None
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